I. Field of the Invention
The present invention relates generally to internal combustion engines and, more particularly, to an improved rotary intake and exhaust valve construction.
II. Description of the Prior Art
Conventional internal combustion engines include a housing with at least one piston member reciprocally mounted within a cylinder formed in the housing. Fuel intake passage means formed in the housing supply fuel to the cylinder for combustion while, similarly, the exhaust gases from the cylinder pass through exhaust passage means formed in the housing and to the engine exhaust system.
In order to permit the intake of fuel into the cylinder and the expulsion of exhaust gases from the cylinder at the desired engine cycles, an intake valve and an exhaust valve are provided in the intake and exhaust passage means, respectively. These valves permit fluid flow or communication through their respective passage means upon opening and, conversely, when closed prohibit such fluid flow.
There are many different types of previously-known intake and exhaust valves. One type of previously-known valve member employs a circular closure plate with an axially attached elongated stem. The plate cooperates with a valve seat formed in the housing while a spring attached to the elongated stem normally urges the valve to its closed position. Conversely, opening of the valve is accomplished by depression of the valve stem by a cam, rocker arm, or other appropriate means. This simple type of engine valve, however, is disadvantageous due to its high cost which, in turn, results primarily from the multiplicity of components required for the valve and its actuation. Moreover, these previously-known engine valve systems are both heavy and bulky in construction.
A rotary engine valve forms another previously-known engine valve in which an elongated cylindrical valve member is rotatably mounted within the engine housing in the fuel intake or exhaust passage means for at least one, and preferably several, engine cylinders. Diametric throughbores are provided through the cylindrical valve member so that upon rotation in synchronism with the internal combustion engine, the valve members permit fluid flow through the intake or exhaust passage means via the diametric throughbore at preselected rotational positions of the valve member. These previously-known engine rotary valves are advantageous over other types of engine valves in that the rotary valves are relatively inexpensive to construct and install. The previously-known rotary valves are additionally advantageous in that such valves are compact and lightweight in construction.
Despite the advantages of the rotary valve, such valves have not enjoyed wide-spread use or acceptance in the industry. One reason for this is that the rotary valves, and particularly the exhaust valve, are subjected to high temperatures from the engine cylinders and tend to warp when overheated. Warpage of the rotary valve not only disables the engine, but also requires expensive replacement of the valve.
A still further disadvantage of these previously-known rotary valves is that the valves must be journalled in high temperature precision bearings. Such bearings are almost prohibitively expensive, but nevertheless required to withstand the normal operating temperatures to which the rotary valve is subjected.
A still further disadvantage of these previously-known rotary valves is that no previously-known sealing means has been heretofore known for adequately sealing the rotary valve to the engine housing particularly after long usage. Consequently, these previously-known rotary valves suffer from fluid leakage around the valves which in turn causes engine compression loss and carburetor blow-back.